Concrete structural component and casting frame



June 7, 1966 F. MOSELEY 3,254,463

CONCRETE STRUCTURAL COMPONENT AND CASTING FRAME Filed Jan. 24, 1963 INVENTOR. F E'ANC/S L. MUSE-L5) ZQMeL A 7TORNE ys subjected to considerable stresses.

United States Patent 3,254,463 CONCRETE STRUCTURAL COMPONENT AND CASTING FRAME Francis L. Moseley, 700 Flintridge, Pasadena, Calif. Filed Jan. 24, 1963, Ser. No. 253,670 3 Claims. (CI. 52-450) This invention relates to concrete structural components having an interior aperture and to an aperture defining casting frame for use in casting such structural components.

Concrete components such as wall sections, slabs and the like are extensively utilized in the construction of certain types of industrial and commercial buildings. Concrete wall sections, slabs and the like are conventionally fabricated by pouring fluid concrete into an outer casting frame while the latter is in a horizontal position, i.e. on the ground. If the wall section is to have apertures such as window openings, door opening or the like, suitable aperture-defining casting frames are placed within the outer casting frame before the concrete is poured. The concrete is then poured between the aperture casting frames and'the outer casting frame. Such frames are usually constructed of wood, steel or other durable material sufliciently strong to retain the desired shape during setting of the concrete. The frames may be coated along their outer surfaces, as with grease, oil or the like to facilitate their removal from the section after the concrete has set to solid form.

After the concrete has set and the frames have been removed, the horizontally disposed section is then tilted up into a vertical position for appropriate installation into the building being constructed.

During the described tilting operation and during subsequent installation and use of concrete section, it may be Concrete sections which contain interior apertures, such as window and door openings, frequently crack, the corners of the apertures being special points of weakness in the concrete. Movement of the concrete section into position, placing a load in the concrete section, shrinkage of the concrete itself, settling of the building foundation and large fluctuations in environmental temperature contribute to the production of stresses in the concrete which results in such cracks. The cracks are not only unsigntly and require time-consuming patching, but represent areas *of structural we'akness in the'concrete'section, reducing its overall strength and durability, even after the cracks are patched.

. In certain instances attempts have been made to mini mize cracking of the wall sections. In this regard, metal rods have been embedded in the unset concrete atvarious points, including areas adjacent each corner of the apertures in the section. Where large shearing forces act in the plane of any aperture, additional reinforcing rods may be embedded in the concrete around such aperture. Moreover, if a whole series of apertures are provided in a line along the concrete section, the concrete is sometimes reinforced with girders, both above and below the apertures.

The extent of reinforcement around apertures in concrete sections has varied considerably, depending upon many factors. Despite such reinforcement, cracks frequently spread from the corners of the apertures within.

Accordingly, it is a primary object of the present invention to provide aperture-containing cast structural components having a reduced tendency to crack at aperture corners.

It is a further object of the present invention to provide improvements in aperture-defining casting equipment for use in the fabrication of concrete structural slabs and the like.

- These and other objects are accomplished, in accordance with the present invention, by employing a method and means which relieve stresses in the corners of interior apertures in concrete components. The apertures are formed so as to include arcuately shaped corner extensions of substantially increased surface area, in contrast to the usual square or 90 aperture corners. Stresses in the concrete defining the corner extensions are equalized along the perimeter of the corner extensions, minimizing the tendency of the concrete to crack, even when subjected to considerable stress-inducing forces.

In order to provide a finished aperture of conventional design, corner extension inserts are disposed in and at least partially fill the corner extnesion areas after the slab is set. The inserts define along their-inner surfaces the desired square or 90 corners, or any other desired corner configuration.

A bettter understanding of the invention may be obtained by reference to the following detailed description, taken in conjunction with the accompanying drawings, of which:

section benig raised into a vertical load-bearing position;

FIG. 2 is a schematic perspective of the section of FIG. 1, in a vertical position, said section containing a plurality of interior apertures, cracking of the 'concrete at the aperture corners being illustrated;

FIG. 3 is a schematic plan'view of an aperture-defining concrete casting frame in place in a portion of a concrete section, the frame incorporating one embodiment of the corner extension member of the present invention;

FIG. 4 is an enlarged schematic fragmentary side elevation of a cast concrete structural slab illustrating a corner of an aperture containing one embodiment of the corner extension insert of the present invention; and,

FIG. 5 is an enlarged schematic perspective of a second embodiment of the corner extension member of the present invention with an integral corner extension insert.

It has been found that cracking at the corners of interiorapertures in concrete and similar building components can be minimized if such corners are provided with extensions which are of substantially increased surface area and of special shape, i.e. arcuately shaped or generally circular in outline, preferably generally cylindrical and having a cross-section in the form of several quadrants of a circle symmetrically generated around the extension. Cracking is thereby avoided. In order to moreuniformly distribute the stresses, the corner extension is preferably shaped to form, in cross-section, three quadrants of a circle, with the center of the circle at the apex (acute or obtuse angled corners, etc), the inserts are the thickness of the concrete section.

. Corner extension inserts areutilized to provide the aperture with square corners or corners of special-shape Patented June 1966 FIG. 1 is a schematic side elevation of a concrete placed in the corner extensions, each insert preferably conforming generally to the shape and size of the corner extension and also defining along its inner surfaces the desired inside corner of the aperture.

The production of the desired corner extensions in the interior apertures of the concrete slab is carried out during the casting of the slab itself and, for this purpose, an aperture-defining frame assembly such as that schematically illustrated in FIG. 3 of the accompanying drawings can be utilized. In accordance with the present invention, corner extension members are incorporated in the frame. After the slab has been cast (usually in the horizontal position) and has set and the frame has been removed, the corner extension inserts can be connected in the corner extensions of the aperture, before or after raising of the concrete section into a vertical position.

Now referring more particularly to FIG. 1 of the accompanying drawings, a typical tilting operation is schematically illustrated, in which a cast concrete section 6 is being moved from the horizontal position (dotted outline) in which it was cast to a vertical position, by suitable means 7, such as a crane 8, with grappling line 9 and hooks 10. The section 6 may comprise one such as schematically illustrated in perspective view in FIG. 2 and containing two interior apertures comprising 'a window opening 11 and door opening 12. As shown in FIG. 2, conventional concrete slabs, such as section 6, frequently develop cracks 13 radiating from the aperture corners, during the tilting operation, or during or after assembly into the building being constructed.

Specific means for minimizing the occurrence of such cracks are illustrated in FIG. 3.

.Now referring more particularly to FIG. 3, a typical aperture-defining concrete casting frame 14 is schematically illustrated in plan view in position in a portion of a concrete section 15. The frame may be fabricated of steel, wood or similar durable strong material having a width conforming to the thickness of the concrete section. The frame 14 may include longitudinally extending wall members 16 generally defining the aperture 17 and interconnected at the corners 18 thereof with stress-relieving corner extension members 19, as shown in FIG. 3. Each corner extension member 19 is connected to adjacent wall members by any suitable means 20, for example, bridging plates 22 with threaded bolts 26 and nuts 24, or the like extending through aligned apertures (not shown) in the members 16 and 19. The plates 22 may ex tend along the adjoining inner faces 30 and 32, respectively, of the wall members 16 and the corner extension members 19. It will be understood that, if desired, the corner extension members 19 can be'formed integrally with the remainder of the frame.

As clearly shown in FIG. 3 of the accompanying drawings and as previously described, the corner extension members 19 are arcuately shaped. More particularly, they are generally circular in cross-section, the cross-section comprising a major portion of a circle. Preferably, each of the corner extension members 19 is constructed to present along its periphery a portion of a cylinder which in cross-section is three quadrants of a circle. The width of a typical cylindrical corner extension member can be more readily seen by reference to FIG. illustrating in perspective view a second embodiment of the extension member.

In accordance with the casting method of the present invention, the frame 14, or a similar frame incorporating the corner extension members, is placed in a horizontal position and concrete or other flowable settable structural slab-forming material is then poured around the outside of the frame 14 and within an outer slab-forming frame (not shown). The concrete is allowed to set, after which the frame is removed, so that an aperture remains in the section 15, the aperture containing the desired corner extensions which are arcuate or generally circular in outline.

Further in accordance with the present invention, either before or after the set section 15 is moved into position in the construction of a suitable building or the like, a corner extension insert 34, as shown in FIG. 4 is fitted into each of the corner extensions 36 which have been provided by the corner extension members 19 during the casting operation. Each insert 34 is shaped to generally conform to the periphery of the corner extension 36 in which it is fitted and is further shaped to define along its inner surfaces 33 a square of inside corner continuous with the ends of adjoining walls 40 defining the aperture. The insert can be fabricated of any suitable structural material, but preferably is of the same structural material as the remainder of the slab, for example concrete if the slab is concrete. Insert 34 is cemented, plastered, pinned or otherwise permanently secured in position in the corner extension 36. If desired, the insert 34 can be fabricated of material such as steel which further increases the strength of the corner extension area.

In the embodiment illustrated in FIG. 5 of the accompanying drawings, a corner extension insert 42 is illustrated which is integrally connected to and forms part of a corner extension member 44. The insert 42 has the added function of bracing a frame (not shown) to which the member 44 is releasably connected when the described casting procedure is carried out. After the casting material (concrete or the like) is set, the remainder of the frame (not shown) can be removed from the corner extension members 44, which can then be left in place in the concrete slab (not shown). Sufiicient adhesion may exist between members 44 and the adjoining portions of the slab to firmly secure the members 44 in place in the slab. Alternatively, members 44 can be further secured to the slab, as by cementing, plastering, pinning, etc. It will be noted that the respective inner faces 48 of the insert 44 and 50 of the extension member 44 illustrated in FIG. 5 are adapted to provide an aperture with a square corner can be continuous with adjoining aperture-defining walls. I

It will also be understood that the corner extension inserts may be constructed so as not to substantially till the corner extension areas, as does insert 34, but so as to merely connect with the slab material or corner extension member defining the corner extension area at one or a plurality of points. Thus, for example, the corner extension inserts may be of generally spider-like or cog-like design (not shown). In any event, the inner surfaces of such inserts, as with the inserts previously described, would form suitable finished inside corners for the aperture with which they would be associated.

It will be further understood that the described corner extension members and inserts can be adapted for use with a large variety of types of aperture-containing casting frames, in addition to the specific frame described.

The described improvements in a casting frame and the described casting method provide means whereby aperture-containing concrete and similar structural slabs can be conveniently fabricated in improved form. Internal apertures of such slabs'are less subject to cracking, particuarly at the corners of the apertures. Moreover, the slabs are stronger and more easily able to resist internal stresses.

While there have been described various aspects of the present invention for producing the improved structural components, it will be appreciated that various modifications, variations and alternative forms are within the scope of the invention. Accordingly, the invention should not be considered to be limited by the foregoing description, but should be taken to include the apparatus and products falling Within the scope of the appended claims.

What is claimed is:

1. In an aperture-defining casting frame for use in the fabrication of structural components, which frame includes longitudinally extending wall members generally defining an aperture, the improvement which comprises generally arcuately shaped, stress-relieving corner extension members releasably connected toadjacent wall members of said frame for retention in the fabricated structural component after the frame wall members are removed, each of said extension members being generally cylindrical and having a cross-section comprising three quadrants of a circle symmetrically disposed about a corner of said frame.

2. A concrete structural component having at least one generally arcuately shaped, stress-relieving inner surface extending about an interior corner of said component, and an insert positioned Within the arcnately-shaped inner surface and shaped to complete said interior corner.

3. A component in accordance with claim 2 wherein said insert comprises a hollow channel extending adjacent the arcuately shaped inner surface, and a filler member within the channel and shaped to complete said interior corner.

References Cited by the Examiner UNITED STATES PATENTS 2,557,631 6/1951 Callan 25-128.1 2,787,820 4/1957 Shields et a1 25.l18 XR FOREIGN PATENTS 735,068 8/ 1955 Great Britain.

OTHER REFERENCES DuBois, I. H. and Pribble, W. I.: Plastics Mold Engineering, Chicago, Amer. Tech. 800., 1946, pp. 55 and 57 relied upon.

Delmonte, 1.: Plastics in Engineering, Cleveland, Penton Publ. Co., 1940, page 273 relied upon. 5 ALEXANDER H. BRODMERKEL, Primery Examiner.

A. L. LEAVITT, Assistant Examiner. 

1. IN AN APERTURE-DEFINING CASTING FRAME FOR USE IN THE FABRICATION OF STRUCTURAL COMPONENTS, WHICH FRAME INCLUDES LONGITUDINALLY EXTENDING WALL MEMBERS GENERALLY DEFINING AN APERTURE, THE IMPROVEMENT WHICH COMPRISES GENERALLY ARCUATELY SHAPED, STRESS-RELIEVING CORNER EXTENSION MEMBERS RELEASABLY CONNECTED TO ADJACENT WALL MEMBERS OF SAID FRAME FOR RETENTION IN THE FABRICATED STRUCTURAL COMPONENT AFTER THE FRAME WALL MEMBERS ARE REMOVED, EACH OF SAID EXTENSION MEMBERS BEING GENERALLY CYLINDRICAL AND HAVING A CROSS-SECTION COMPRISING THREE QUANDRANTS OF A CIRCLE SYMMETRICALLY DISPOSED ABOUT A CORNER OF SAID FRAME.
 2. A CONCRETE STRUCTURAL COMPONENT HAVING AT LEAST ONE GENERALLY ARCUATELY SHAPED, STRESS-RELIEVING INNER SURFACE EXTENDING ABOUT AN INTERIOR CORNER OF SAID COMPONENT, AND AN INSERT POSITIONED WITHIN THE ARCUATELY SHAPED INNER SURFACE AND SHAPED TO COMPLETE SAID INTERIOR CORNER. 